This invention relates to ophthalmic surgery, and in particular, to surgery on the cornea.
The cornea of the eye plays a role in focusing light. By changing the shape of the cornea, it is possible to correct a patient""s vision. Common surgical procedures for changing the shape of the cornea include temporarily removing the epithelium of the cornea to expose the underlying stroma, ablating selected portions of the stroma with a laser, and replacing the epithelium over the stroma.
In LASEK (xe2x80x9cLaser assisted Sub Epithelial Keratomilieusisxe2x80x9d) surgery, an incision along a circular arc on the cornea is made and the resulting flap is pulled back to expose the stroma of the cornea. The flap includes the epithelium and the Bowman""s membrane separating the epithelium from the stroma. Unlike the flap that is made during LASIK (xe2x80x9cLaser assisted In situ Keratomilieusisxe2x80x9d), this flap does not include any portion of the stroma. Thus, when the flap is pulled back, it is the surface of the stroma, and not the interior of the stroma, that is exposed to the laser. This procedure thus results in a lower risk of complications.
In practice, because the epithelium is so thin, it is difficult to cut a flap without also cutting into the stroma.
In one aspect, the invention includes an apparatus for forming a corneal flap. The apparatus includes a housing from which a shaft and a reciprocating member extend. At the distal end of the shaft is mounted an aplanating member for aplanating a region of the cornea. At the distal end of the reciprocating member is mounted a cutting blade for slicing an aplanated region of the cornea.
In some embodiments, the aplanating member is a roller, while in other embodiments, the aplanating member is a runner.
The cutting blade can be a wire, a knife, or any other structure configured to slice into the cornea.
In some embodiments, the aplanating member and the cutting blade are offset by an amount corresponding to a desired thickness of the flap. The aplanatihg member can be offset from the cutting member in either the proximal or distal direction.
Another aspect of the invention is an apparatus in which a forked end of a shaft defines a gap. An aplanating member, for aplanating a region of the cornea, extends across this gap. The apparatus also includes a reciprocating member having a distal tip formed into a bow. A cutting blade extends across this bow and is disposed to slice the aplanated region off the cornea.
In another aspect, the invention provides a method for forming a corneal flap by aplanating a region of the cornea and placing a reciprocating cutting blade on the aplanated region. The flap is then formed by translating the cutting blade across the aplanated region.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.